Automation in the automotive industry, the aircraft industry and the like is always advancing, and with the robots used for this, through improvements in sensing technology, control technology and the like, it is becoming possible to realize complex work at a higher level. In recent years, for example, spot welding, deburring, chassis lifting and the like in the automotive manufacturing process are almost all done by robots, and the ratio of work performed by robots in manufacturing processes is very high.
However, specially preparing robots equipped with tools such as spot welding guns used for welding, cutting tools used for deburring, manipulators for handling chassis and the like is not desirable from the perspective of the expense for building the production line, factory space efficiency and the like.
In light of this, for example an automatic tool exchange device noted in Patent Document 1 or Patent Document 2 is used. This automatic tool exchange device is typically constituted so that a first coupling member attached to one of either the robot main unit side or the tool side and a second coupling member attached to the other are able to be separated from and coupled to each other. By doing this, tool exchange is possible, and it is possible to handle a plurality of tools with one robot.
Then, depending on the used tools, various modules are provided that, between the first coupling member and the second coupling member, make it possible to transmit electrical signals or power, or make it possible to supply a liquid or gas. These modules are constituted in pairs of a first module attached detachably to the first coupling member, and a second module attached detachably to the second coupling member, and by coupling the first coupling member and the second coupling member, the first module and second module are coupled to each other. Then, in this coupled state, it is possible to transmit electrical signals or power, or to supply liquid or gas between the first module and the second module. Here, the modules that make it possible to transmit electrical signals, as noted in Patent Document 1, almost all have this performed by the pin contact point by having a pin projecting from one of the first and second modules be in contact with a terminal provided on the other.
However, robots used in production factories have the tools moved quickly to reduce takt time, so significant acceleration is applied to the connecting parts of an automatic tool exchange device. In light of this, many automatic tool exchange devices allow a certain amount of play while maintaining the coupled status between the first coupling member and the second coupling member in order to reduce the load when moving with high acceleration. Because of that, when large acceleration is applied to the automatic tool exchange device, by the first module and the second module being separated from each other, there was the risk of a contact failure occurring because of a separation between the pin and the terminal. A contact failure of the pin contact points brings on electrical signal transmission failure, and was a cause of a decrease in processing precision due to not correctly obtaining various types of sensing information by the position sensor attached on the robot, for example, or bringing on emergency stopping of the robot in some cases, reducing production efficiency.
Also, within a production factory, because work machines such as a large number of robots are operating together with work such as welding, painting, cleaning or the like being performed, it is easy for this to become a high temperature, high humidity environment, and for pin contact points, contact failure occurred easily as well in a high temperature, high humidity environment. Furthermore, because there is the risk of contact failure occurring due to dust, slag or the like entering between the pin and the terminal, the occurrence of wear, deformation, a film or the like due to repeated connection, time and effort were required for maintenance such as regular examination or cleaning of pin contact points or the like. In addition, damage occurs easily due to the pins projecting, so both members need to be aligned with good precision so as not to break the pin when coupling the first coupling member and the second coupling member, and the work of exchanging tools required time.
To avoid these problems, for example as noted in Patent Document 3, using data communication technology that is wireless such as a wireless LAN or the like, it is possible to perform sending and receiving of electrical signals on the robot main unit side and the tool side. However, robots used in production factories require high level real time properties to operate quickly according to signals from the position sensor for accurate aligning of tools or the like, for example. Nevertheless, wireless data communication requires a large number of processes for the generation of sending data packets on the sending side and the restoring of data by the receiving side, and there is the risk of losing responsiveness. Also, in an environment in which a large number of robots are operating simultaneously, when attempting to control each robot wirelessly, it is impossible to avoid the problems of interference and noise mixing in, so this was not realistic.